In vehicles, building systems, portable electronic devices, and other systems, it is often desirable to provide structures that modify the propagation of light. For example, windows are sometimes provided with frosted surfaces or mirror coatings to enhance privacy.
It can be challenging to incorporate structures for modifying the propagation of light into windows. If care is not taken, windows may be too reflective, may be insufficiently transparent for viewing, or may have other undesired attributes.